Various publications, including patents, patent applications, technical articles and scholarly articles are cited throughout the specification. Each of these cited publications is incorporated by reference herein, in its entirety and for all purposes.
The success of implanted surgical repair materials is highly variable. This variability is compounded when considering procedures where the repair material must support both an immediate post-operative biomechanical load, as in for example repair of abdominal wall hernia defects or other procedures (wherein replacement or strengthening of soft tissue is required or desired), and subsequently maintain the desired repair characteristics over the expected duration of the implant.
Some commonly available repair materials for hernial or other soft tissue defects include synthetic meshes and collagen based sheets of allogeneic or xenogeneic material. Each of these suffers from inherent limitations that may make them less than optimal for the full and immediate repair of such a defect. Synthetic meshes, while possessing good tensile characteristics, do not necessarily integrate with the patient's body and over time may become a source of adhesions as they are progressively infiltrated with or covered by scar tissue. Additionally, synthetic meshes are more prone to infection, which often leads to subsequent removal and replacement.
Collagen sheets, often derived from human or animal skin, pericardium, intestinal tissue or bladder or constructed from collagen suspensions, are often cross-linked to render them inert or minimally reactive to the patient's body and to provide some increased mechanical strength. This cross-linking process devitalizes the repair matrix, preventing proper infiltration, adherence and remodeling by the patient's cells and resulting in a similarly non-integrative material. A subset of implantable collagen matrices are those that are chemically processed to remove cellular and antigenic components and are often described as revitalizing tissue matrices (RTM). These RTMs have been shown to populate with a patient's own cells as part of a healing response. Infiltration by cells such as fibroblasts enables the patient's innate repair mechanisms to guide the regeneration of viable tissue at the surgical repair site. However, these RTMs suffer from a lack of initial mechanical strength and therefore may not be indicated where high initial tensile properties are required, as in abdominal wall repairs. Similarly, RTMs often suffer from an accommodation response post-implant, wherein the implanted material irreversibly and detrimentally deforms in response to the inherent stresses imposed on it. If not managed or corrected, this condition may result in substantial laxity to the repair site, or failure of the graft, which must be corrected in follow up procedures.
There remains a need for controlling the strength and pliability of such implants. It is believed that such control promotes proper healing and revitalization of the tissue or anatomical area being repaired, and also may prevent failure of the implant under biologic load stress within the body.